Light-sensitive materials are generally prepared by coating a photographic light-sensitive emulsion layer (hereinafter referred to simply as a "light-sensitive layer"), an antihalation layer, a protective layer, an intermediate layer, a subbing layer, a backing layer (hereinafter referred to simply as a "back layer"), and so forth on an insulative plastic film support.
In recent years, techniques for production of light-sensitive materials have been markedly improved; for example, coating speeds for each layer and cutting speeds of light-sensitive material have been greatly increased.
Also, handling speed of light-sensitive material during photographing and transportation speed of light-sensitive material during development processing have been greatly increased.
During the production of light-sensitive materials or in the use thereof, therefore, contact friction and peeling-apart of the light-sensitive materials with itself, or between the light-sensitive materials and other materials readily occur, tending to cause the generation of static electricity.
As is well known, the generation of static electricity in light-sensitive material leads to attachment of dust, etc., onto the light-sensitive material, resulting in the occurrence of various problems, and when the generation of static electricity is vigorous, spark discharge can occur, causing the formation of so-called static marks, which is a critical problem.
Heretofore, as antistatic agents for use in a back layer, polymeric electrolytes or surface active agents have been often employed. However, the effect of these polymeric electrolytes or surface active agents in reducing the generation of static electricity greatly varies depending on humidity; that is, at high humidities, electrical conductivity is obtained to the extent that the intended objects can be attained, whereas at low humidities, the electrical conductivity may be significantly reduced. Furthermore, when allowed to stand in the state that it is superposed on the light-sensitive layer, such as when coiled in a roll, the back layer absorbs moisture and adheres to the surface of the light-sensitive layer, causing a problem of adhesion.
Furthermore, polymeric electrolytes and low molecular weight surface active agents are generally water-soluble, and therefore, during development processing, they are dissolved in the processing solutions, and may combine together with other substances contained in the processing solutions to cause the formation of turbidity and sludge, or they may cause other substances to be absorbed onto the back layer, forming uneveness.
In order to solve the problem of adhesion, a method has been employed in which colloids of non-crystalline inorganic oxides are used. In accordance with this method, however, when inorganic oxide colloid sols are used, the antistatic properties deteriorate after development. Furthermore, this method fails to improve sufficiently the dependence of antistatic properties on humidity.
In addition, a method has been proposed in which a carbon black dispersion layer is provided for both antihalation and prevention of the generation of static electricity. This carbon black layer, however, is removed during development processing, and thus after development the antistatic properties are lost.